Elimination and evaluation of welding residual stress in sterilizers welded by combined process

Observing that cracks appear simultaneously on multi-location near weld on intracavity of domestic vacuum, we investigate a series of studies on welding residual stress and its corresponding elimination methods.We design seven types of combined-structure plates and quantitatively measure the residual stress distribution by X-ray method based on the characteristics of discontinuous welding of different steel in sterilizers.The results show that welding residual stress of all seven types of boards reaches yield stress and causes the stress corrosion and corrosion fatigue which are main reasons of the intracavity cracking of sterilizers.In addition, residual stress resulted from carbon dioxide welding is 10%-22% higher than manual welding, and residual stress is indifferent with rebar type.After experimental verification of post-welding watering quick-cooling technology to eliminate the residual stress, we conclude that watering quickcooling can effectively reduce the surface residual stress by 50%-70% and increase fatigue limit by 12%-14% on watering surface.Reducing welding residual stress is an important way to solve the problem of cracking in the intracavity of sterilizers.